MATTHEY1 investigated the cytology of the Monotremes and recognized a division into macro- and micro-elements similar to that in birds, and obtained a value of 70 ± 10 for the diploid number. Van ...

A new study suggests the platypus and echidna — the only egg-laying mammals — had a water-dwelling ancestor. The finding could upend what’s known of their evolution.

Monotremes, found only in Australia and New Guinea, are unique mammals that lay eggs, combining features of reptiles and mammals. This group includes the platypus and four echidna species. They ...

In almost all mammals, male sex-determination occurs via the SRY gene on the male Y chromosome. Monotremes have evolved a totally different sex chromosome system that lacks the SRY gene.

Australian researchers have found evidence of the oldest known platypus and a new species, dubbed 'echidnapus', which has a platypus-like anatomy alongside features that more closely resemble an ...

For decades, scientists have known that platypuses and echidnas – Australia’s unique egg-laying mammals – have another developmental quirk: they don’t use the same genetic toolkit as other mammals to ...

A new study suggests the platypus and echidna — the only egg-laying mammals — had a water-dwelling ancestor. The finding could upend what’s known of their evolution.

Six monotremes living in the same place at the same time, 100 million years ago at Lightning Ridge, NSW. Clockwise from lower left: Opalios splendens, a newly described species dubbed an ...